The number and types of wireless devices and wireless standards has seen rapid growth in recent years and is unlikely to slow anytime soon. Consequently, available frequency bands, which are regulated by organizations such as the FCC in the USA, are becoming increasingly scarce. Moreover, existing frequency bands are becoming increasingly congested with wireless traffic from the plethora of users and devices in existence. In this regard, designing devices that can reliably operate in such noisy frequency bands is becoming increasingly difficult and costly. Accordingly, efforts exist to develop wireless technologies which operate at higher, less congested frequencies.
For example, in 2001, the Federal Communications Commission (FCC) designated a large contiguous block of 7 GHz bandwidth for communications in the 57 GHz to 64 GHz spectrum. This frequency band may be used by the spectrum users on an unlicensed basis, that is, the spectrum is accessible to anyone, subject to certain basic, technical restrictions such as maximum transmission power and certain coexistence mechanisms. The communications taking place in this band are often referred to as ‘60 GHz communications’. With respect to the accessibility of this part of the spectrum, 60 GHz communications is similar to other forms of unlicensed spectrum use, for example Wireless LANs or Bluetooth in the 2.4 GHz ISM bands. However, communications at 60 GHz may be significantly different in aspects other than accessibility. In this regard, there may be certain drawbacks associated with 60 GHz communications. For example, 60 GHz signals may provide markedly different communications channel and propagation characteristics. In this regard, 60 GHz radiation is partly absorbed by oxygen in the air. Accordingly, 60 GHz communications suffer from increased attenuation with distance as compared to, for example, 2.4 GHz. On the other hand, there may be advantages associated with 60 GHz communications. For example, since a very large bandwidth of 7 GHz is available, very high data rates may be achieved.
Shrinking features size of CMOS processes, for example, is one factor enabling development products and technologies for 60 GHz communications. However, even when fabricated on the smallest processes, conventional methods and circuit topologies are often unable to realize signal generation circuits which can generate signals sufficiently high in frequency to enable technologies such as 60 GHz communications.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.